Temporary Traffic Management (TTM) techniques for relaxation scheme road works require road workers to set out advance warning signs, an activity which exposes them to high risk. Therefore alternative measures for providing advance warning signs in order to inform road users that there are road works ahead are being developed. This research project has specifically sought to evaluate the use of MS4 Variable Message Signs (VMS) instead of conventional signs on A-frames at ground level.

Outcome 1
The assessment of the effectiveness of MS4s as the sole means of signing works was achieved primarily by analysing traffic behaviour during a series of lane closures signed using the existing method (control) and comparing this against driver behaviour during a series of lane closures signed using MS4 VMS (experimental).
The on-road trial was successful in demonstrating that the use of MS4 VMS to display the advance warning of lanes open and lanes closed for road works are at least as effective as current IAN 150/14 Revision 2 / Chapter 8 TTM.
For nearside (lane 1) closures, the results showed that the pattern of vehicles changing lanes between the 800m to 400m distances did not differ between the experimental and control groups, and that the pattern of vehicles changing lanes between the most upstream sign containing lane closure information and the 400m sign did not differ between the experimental and control groups.
For offside (lane 3) closures, the results showed that the pattern of vehicles changing lanes between the 800m to 400m distances did not differ between the experimental and control groups. The pattern of vehicles changing lanes between the most upstream sign containing lane closure information and the 400m sign differed in the middle lane, which was not safety-critical.

Outcome 2
The Measurement of Injury Risk (MIRi) Index applies to the deployment and retrieval of TTM for relaxation closures, considering the risk to road workers only. The MIRi tool quantifies risk providing an indication of the relative risk to road workers when installing and removing TTM using various techniques including those already in widespread use by the Traffic Management (TM) industry.
The omission of conventional signs on A-frames at ground level in advance of the road works was examined using the principles of the MIRi Index. This estimated that the risk to road workers when installing and removing TTM using only MS4s to provide advance warning signing is 18% lower for nearside closures than when using Off Side Signs Removal, and 30% lower for offside closures than when using Sign Simplification. It is safer still relative to the risk to road workers when installing and removing a full Chapter 8 relaxation layout.
The risk reduction arises from the reduction in total time it takes to install/remove the closure and the elimination of carriageway crossings to install the advance warning signs.

Outcome 3
The likely implications for – and the impacts on – the Traffic Officer Service (TOS) which is responsible for the management of VSS were considered in terms of both the availability of the technology infrastructure and staffing resources through an analysis of data and feedback from East Regional Control Centre (ERCC) staff. The on-road trial provided an understanding of the likely impact upon the TOS and the dependency this technique will have on MS4 VMS availability.
The greatest impact upon the TOS is related to the level of resource that was required for this trial to constantly monitor the accuracy of the electronic setting displayed on the MS4s. Availability of fully functional MS4s (i.e. ones not exhibiting faults) was relatively low, with 29% of the required MS4s – and subsequently 66% of planned trials – being affected by a fault on one or more of the MS4s. The trial did not observe any occurrence where the availability of the MS4s was affected due to normal operations i.e. by an unplanned incident.

Recommendations
The reliability of the MS4s is currently likely to be insufficient for them to be used as the sole method for signing relaxation works, irrespective of whether this approach is comparable to using ground level signing in terms of road user behaviour.
Assuming these technological issues can be resolved, other changes to the current way of working would also be required to ensure that MS4s can be used to provide drivers with suitable advanced warning of road works. For example, the Agency would require a system which is intelligent enough and flexible enough to allow simultaneous signalling of incidents and road works. A dedicated system alarm for any VSS in use as the sole method for signing road works would also be beneficial.
Other approaches that would represent a more significant shift from the current approach to managing Variable Signs and Signals (VSS) could mitigate the risk associated with this approach. For example:
• Management of VSS used to sign road works from a centralised unit, so that all Regional Control Centre (RCC) operators are able to operate all VSS across the network. This would make it more likely that an RCC operator would be available to deal with a VSS failure immediately that this is alerted.
• Providing on-road staff with alerts directly when the VSS relevant to their works fails. This would remove the risk of a delay in an RCC operator informing on-road staff of the failure.
• Providing TM staff with the ability to control the relevant VSS in full, whether temporarily or otherwise. This would ensure that TM staff fully own the risk to on-road staff that would be associated with VSS failure. This could include testing of the relevant VSS in advance. This approach would require appropriate protocols for control of the VSS to be handed over temporarily from National Traffic Information Centre (NTIC) and the RCC to TM staff, so that they do not unwittingly overwrite the VSS. Although this approach is not dissimilar to the current situation, TM staff would be less likely to be aware of what is occurring on adjacent sections of the network, so this might introduce the risk that an incident close to the works is not signed.

Want to know more about this project?